Smart antennas and reconfigurable antennas have been used in applications for wireless network communications including communications via radio-frequency identification (RFID) tags and for Wi-Fi devices, and they provide many beneficial features in these applications. However, they are overly complex and expensive to make and use. Smart antennas, which are also known as adaptive array antennas and multiple-input multiple-output (MIMO) antennas, are highly adaptable devices that use complex algorithms and modifiable antenna configurations to communicate effectively on a wireless network. However, these highly adaptable devices require external variable power to support their adaptable configurations, which include changing their antenna configurations, performance and other parameters as needed.
Smart antennas also operate with phase distribution system controls that manage a phased array of antenna devices cooperating with each other to steer radio beams and adapt to network parameters as needed for effective network communications. However, such networks and devices are expensive. Further, they are complicated to design, manage and maintain due to the multiple changeable components required in the antenna devices, not to mention due to the complexity of their control mechanisms that ensure coordinated control of the antenna elements, as well as their need for external variable power requirements.
Reconfigurable antennas likewise include modifiable elements that permit antenna configuration changes to be made, but the antenna device itself in these systems is more compact than with smart antennas. Similar to smart antennas, reconfigurable antennas can be electronically switched as needed to enable and disable communications and modify antenna parameters. Conventional reconfigurable antennas include variable resistors in the form of PIN diodes and small switches in the form of micro-electro-mechanical system (MEMS) switches, which are controlled to modify the antenna configurations.
Both Smart and Reconfigurable conventional antennas require external variable power supplies and DC bias lines in order to provide power for changing their configurations, as well as for supporting their complex logic elements and control mechanisms. Both of these conventional antenna systems also require complex circuitry and support features, such as fiber optic lines, DC biased RF feeds, and other complex circuitry components. As such, conventional Smart and Reconfigurable conventional antennas require complicated antenna designs, complex controls and elaborate control logic for managing the devices, as well as external variable power supplies to enable their operation.
Implementations of RFID tags have included smart and reconfigurable antenna technologies for various purposes included enabling devices to create ad-hoc mesh networks based on tag-to-tag network communications. These systems are used in a many industries for various purposes including indoor and outdoor environments. The tag-to-tag network communications can allow an ad hoc, robust wireless network to be quickly created with minimal infrastructure requirements.
The use of RFID tags for creating ad hoc networks or for other implementations, involving tag-to-tag communications have primarily been limited to active RFID tags. This is because active RFID tags are generally more adaptable allowing them to change communication parameters quickly and more easily than passive tags, and because they can communicate between each other at much greater distances than passive RFID tags. For example, active RFID tag communication distances may be on the order of several hundred feet between tags versus about a foot or so between passive RFID tags. However, the cost of active RFID tags is considerably higher than passive RFID tags, which can often prohibit their usage.